Non-invasive techniques for determining blood flow in the cochlea and imaging its tissue morphology are of paramount importance for the improved understanding, diagnosis, and treatment of sudden sensorineural hearing loss (SSHL) and Meniere's disease. Currently there is no device capable of in vivo measurement of volumetric cochlear blood flow (CoBF) or cochlear tissue morphology. We propose to develop an outpatient imaging instrument that is able to measure CoBF in the human inner ear and categorize the flow level as normal or abnormal. The instrument will also image the position of Reissner's membrane and determine if there is a cochlea hydrops. The instrument can be applied in the outpatient setting and for the first time will provide a metric for determining the basis for, and the form and incidence of 'vascular' SSHL and the rational treatment with vasoactive and anti-inflammatory agents. It will be able to confirm the hydrops form of Meniere's disease diagnosis. The design of the proposed instrument is based on a novel optical imaging modality, 3D optical microangiography (OMAG) and optical coherence tomography (OCT) that we have recently developed. OMAG is able, for the first time, to image the 3D distribution of dynamic blood perfusion, down to the capillary level, within the microcirculation tissue beds at an imaging depth up to 2.00mm into tissue. OMAG produces imaging contrast via endogenous light scattering from moving particles (e.g. flowing blood cells within open vessels), thus no exogenous contrast agents are necessary. It is markedly different from LDF as one may obtain a calibrated metric for the blood flow. Using the OMAG system, we have been able to capture in vivo 3D blood flow images, down to capillary level resolution, from the cochlea in gerbils. The OCT mode of operation of the instrument provided images in the plane passing through the organ of Corti and scala media space that revealed the position of Reissner's membrane. In the proposed research, we aim to design this novel imaging system for in vivo imaging cochlear tissue morphology and CoBF and will test it in an animal model. By its use in humans we expect to define blood flow involvement in SSHL since, with the instrument, blood flow can be systematically investigated for the first time at the resolution level of identifiable vessel classes (artery, arterioles, capillaries, venues and vein). We will correlate the data obtained from use of the instrument with that obtained by high field strength MRI. The project design also includes a clinical arm that aims to translate the technique into the clinical settings. PUBLIC HEALTH RELEVANCE: We propose to develop a novel optical imaging instrument that can provide the simultaneous, quantitative assessment of blood flow and tissue morphology in the cochlea in clinical settings. This novel imaging instrument will become an important tool to improve the understanding, diagnosis and treatment of sudden sensorineural hearing loss and Meniere's disease